RQC Seminar

171st RQC Seminar

• Speaker

  Dr. Sebastian de Graaf
  ( National Physical Laboratory, UK. )

• Date

  14:00-15:00 (2:00 -3:00 p.m.), November 25, 2024 (Monday)

• Venue

  Hybrid(ZOOM・ Room S507 at Wako Chem.＆Mat.Phys. Blgd. (S51))

• Title

  In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
The low-temperature physics of structurally amorphous materials is governed by low-energy two-level system defects (TLS). Being impervious to much of traditional condensed matter probes, the exact origin and nature of TLS remain elusive. Recent advances towards realising stable high-coherence quantum computing platforms have increased the importance of studying TLS in solid-state quantum circuits, as they are a persistent source of decoherence and instability. Here, performing scanning gate microscopy on a live superconducting quantum circuit at millikelvin temperatures, we locate individual TLS, directly revealing their microscopic nature. Mapping and visualising the most detrimental TLS in the bath pinpoints the dominant sources of the ubiquitous 1/f dielectric noise and energy relaxation. Furthermore, we are able to deduce the three-dimensional orientation of individual TLS electric dipole moments. Combining such insights with structural information of the underlying materials can help unravel the detailed microscopic nature and chemical origin of TLS, directing targeted strategies for their eventual mitigation.